In a conventional mobile communication system, as shown in FIG. 1, when a commuter train or the like passes by a boundary region between location registration areas, mobile terminals (a) of all the users in the commuter train start transmitting location registration request signals concurrently. This causes over use of a radio capacity and an increase in processing load on an switching device. As a result, in a location registration area where the reception of the location registration request signals is concentrated, network congestion occurs and thereby access control is performed.
It has been a problem that, when such congestion occurs in the location registration processing, the mobile terminal (a) which is located in the area where the congestion occurs is also under the access control, and thus fails to perform incoming/outbound call processing and location registration processing.
To address such a problem, the 3GPP SAE (System Architecture Evolution) has proposed a “Multiple-TA system” configured to individually assign each mobile terminal multiple TAs (Tracking Areas) with which the mobile terminal has to register its location simultaneously.
As shown in FIG. 2, in the “Multiple-TA system”, each of mobile terminals (A) to (C) is configured to simultaneously register its location with multiple TAs which are allocated to itself.
For example, the mobile terminal (A) is configured to register its location simultaneously with TA (A) to TA (C) in a boundary region between TA(O) (not shown) and TA(A), and to register its location simultaneously with TA(D) to TA(F) in a boundary region between TA(C) and TA(D) (see part (1) of FIG. 2).
To put it differently, the mobile terminal (A) is configured not to register its location in a boundary region between TA(A) and TA(B), for example.
Non Patent Document 1: 3GPP TS23.401 V1.1.0
Non Patent Document 2: 3GPP TS23.882 V1.11.0
Meanwhile, in a “Multiple-RA system” where the “Multiple-TA system” employed in the 3GPP SAE is applied to the current 3GPP mobile communication system, a mobile terminal registers its location simultaneously with multiple RAs as shown in FIG. 3(a) and FIG. 3(b). This raises a problem of making control rough in accuracy because the location registration area is excessively large. In addition, this also raises a problem that a paging amount directed especially to a mobile terminal not supporting “Multiple-RA system” is so increased that the service cannot be provided due to processing capacity, frequency limitation, or the like.